Method of and means for controlling electric currents by and in accordance with light variation



Sept. 4, 1923. 1,46%?01 L DE FOREST METHOD OF AND MEANS FOR CONTROLLING ELECTRIC CURHENTS BY AND IN ACGORDANCE'WITH LIGHT VARIATION Filed Sept. 18 1919 2 Sheets-Sheet 1 INVENTOR w Wwlmgv Sept. 4, 1923. 1,466,701

L. DE FOREST METHOD OF AND MEANS FOR CONTROLLING ELECTRIC CURRENTS BY AND IN ACCORDANCE WITH LIGHT VARIATION Filed Sept. 18, 1919 I 2 Sheets-Sheet 2 QflTOR yum.

)w ATTORNEY O.

Patents-5i Sept. 4, '1923.

UNITED STATES,-

PATENT oFl-lc1 LEE DE ronns'r, or NEW rank, n. Y., ass'renon, BY mnsnn Assremurs, r0 nn ronnsr rnouorrrm conronarron, or JERSEY CITY, new JERSEY, A oonronano or DELA ARE.

mnrnon or AND MEANS FOR cournonrme nmicrnrc coaanu'rs BY AND 11V ACCORDANCE WIT LIGHT vanrarrou'.

Application filed September 18, 1919. Serial No. 324,68 5.

To all whom it may con-cm: Be it known that I, LEE DE FOREST, a citizen of the United States, residing at New York, in the county and State of N ew York, have made a certain new and useful Inven tion in Methods of and Means for Controlling Electric Ourrentsby and in Accordance with Light Variation, of which the following is a specification.

This invention relates to a method of and means for controlling electric currents,and is particularly directed to the control thereof by and in accordance with light variations.

The object of stated, is to provide means for controlling, effecting, generating or altering electric cur: rents by and in accordance with light variations.

Further objects of the invention will ap pear more fully hereinafter.

The invention consists substantially in the construction, combination, location and relative arrangement of, parts together with, the method involved and the circuital arrangements employed in accordance therewith, all

as will be more fully hereinafter set forth,

as shown by the accompanying drawings, and finally pointed out in the appended claims.

Referring to the drawings, Fig. l'is a diagrammatic view of asystem embodying my invention.

Fig. 2is a detail view of a modified arrangement of a portion of thesyst'em shown in Fig. l.

Fig. 3 is a similar view of a modified arrangement.

Figs. 3 and 4 are similar views showing circuital modifications.

The same part is designated by the same reference characters wherever they occur throughout the several views. I

My present invention isdirected to the control of electric currents by and in accordance with variations of light. The useful applications of a system of thisnature are many, one of whichbeing the reproduction of photographically recordedsounds for sound reproduction purposes, for example, in phonographs, talking moving pictures,

etc., the specific uses forming the subjectmatter of copen'ding applications. I do not the invention, broadly -matically illustrated the principles involved,

desire to limit my presentcase to any parand it will be apparent tothose skilled the art how the useful, applications of the 'invention with or without modification in detailsmust logically follow. 4

In Fig. 1 I show a source oflight l'which directs its rays through suitable lenses 2, 3, between which is located a screen, revolving shutter, or the like, 4. In the case of reproduction of sounds from a 'photographically obtained record thereof, the shutter etmay be substituted by the film having the photographically obtained sound record thereon as illustrated diagrammatically in Figs. 2, 3 and 3 I employ two oscillating auditins 5 and 6 with their associated circuits, electri cally associated with each other.

Each 0f the oscillating audions, M05011 lions, generates in the usual manner, oscil lating currents, which may be of either high or low frequency, as desired. The oscillating audion circuits selected for the purpose of.--

illustration are now well known in the radio;

art, and may be briefly described as, in this instance, as an. oscillating circuit, including an inductance 7 and condensers 8 and 9, con-. nected in parallel, which circuit connects the plate electrode lOwith the grid electrode 11 of the audion 6, through the usual stopping condenser 12. A tap connection is provided from the oscillating circuit to' the filament electrode 13, and the filament electrode is lighted from a current source 14, all as is well known and practiced in the art. Likewise a clrcuit is provided in the usual manner from the oscillating circuit to the fila-- ment electrode 13 including the usual B-battery, or current source 15. This last circuit, however, in accordance with my present invention, includes one coil 16 of a transformer, the other coil 17 of which is included in the input or grid-filament circuit of an audion amplifier 18, the output or plate-filament circuit of whichincludes an electro responsive device 19, for example, a tele? phone receiver, loud -speaking horn, or the like. The circuits of oscillatingaudions 5 are essentially the same, and the two oscillating audions are inductively associated with each other through. the coils 7. I prefer to provide a'high resistance leak path 19 .be-

tween the grid and filament electrodes of audions 6, and in a similargrid-filament circuit of oscillating audion 5 I provide in addition to the resistance 19, a source of cur rent 20 and a light sensitive device 21 through which the system is controlled. The light sensitive device, which may be a photoelectric, selenium cell, or the like, is positioned adjacent the lens 3, and in alignment therewith to be affected by the light coming from source 1, as permitted by the shutter, film, screen, or thelike, 4.

By means of the foregoing arrangement a beat note is set up by interference between the two frequencies generated by the audions 5 and 6. The pitch or intensity of this beat note is altered by the amount of resistance in the grid-filament leak path of either oscillion. The beat note or current set up as above explained in the plate or output circuit of oscillion 6 is amplified, if desired or necessary, by the audion amplifier 18, and

detected, or made audible through the telephone receiver or loud speaking horn 19 in the output circuit thereof.

In Fig. 2, in place of the selenium or photo-electric cell 21, I show a small condenser 22, preferably in a partially exhausted glass vessel 23 filled with anionizable gas, the said condenser being in shunt to the condenser 8 of the oscillating circuit of the oscillion 5. In this arrangement the light from the source 1 is directed to the condenser 22, and the capacity of this condenser will be varied according to the uality and degree of light falling thereon rom the source 1. The changes in capacity thus produced by light variations causes corresponding changes in the frequency of oscillations in the circuit of the oscillion 5, and these changes can be detected with or without amplification by the beat method above explained. a

In Fig. 3 I show a modification of the system thus far described, which consists essentially, in employing but one oscillion system, and modulating, by means of the the oscillion, detecting the modulated oscillations, and reproducing the same in the form of sound by means of the telephone receiver, loud speaking horn, or the like. In this instance, the coil 7 of oscillion 5 is inductively associated with the input circuit of the usual audion detector 30, or it may be connected directly to .the input circuit of the first audion 18 of a series of multi-stage amplifiers, in a ,manner well understood in the art and as illustrated in Fig. 3. In Figure 3 I have illustrated the device 21 in the grid-filament leak path of the oscillion 5, as a photo-electric cell, but I wish it to be understood that I d not desire to be limited to any particular type orstyle of light sensitive device.

In Fig. 4 I show another method of connecting the light sensitive device 21 to the 7 grid leak of an audion 5 which may or may not be in an oscillating state. Here a polarizing battery 40 connected around the device 21, as is also a potentiometer resistance 41 from which a sliding contact ful, and of my own invention, and desire to secure by Letters Patent, is,-

1. The combination with a plurality of oscillions and their associated circuits, electrically associated with each other, and each generating undamped oscillating currents, means controlled by light rays for altering the frequency of the oscillations generated by one of said oscillions.

2. The combination with a plurality 1 oscillions and their associated circuits, electrically associated with each other, and each generating undamped oscillating cur rents, means controlled by light rays for altering the frequency of the oscillations generated by one of said oscillions, and means for detecting the alterations so-made.

3. The combination with a plurality of oscillions and their associated circuits, electrically associated with each other, and each generating undamped oscillating currents of different frequency, and a light sensitive device included in one of the circuits of one of said oscillions for altering byand in accordance with light rays the frequency of the oscillations generated thereby.

\ 4. The combination with a plurality of oscillions and their associated circuits, eleclight, the oscillating currents generated by trically associated with each other, and each generating undamped oscillating currents, of different frequency, and a light sensitive device included in one of the circuits of one of said oscillions for alteringby and in accordance'with light rays the frequency of the oscillations generated thereby, and

means for detecting the alterations so made. 5. The combination with a plurality of oscillions and their associated circuits, electrically associated with each other, and

each generating undamped oscillating currents of different frequency, and a light sensitive device included in the grid circuit of one of said oscillions for altering by and in accordance with light rays the frequency of the oscillations generated thereby.

6. The combination with a plurality of oscillions and their associated circuits, electrically associated with each other, and each generating undamped oscillating currents of diiferent frequency, and a light sensitive device included in the grid circuit'of one of said oscillions for altering by and in accordance with light rays the frequency of the oscillations generated thereby, and means for detecting the alterations so made.

7. The combination with an audion, of a light sensitive device included in a circuit connecting the grid and filament electrodes of said audion, and a source of current included in said circuit and shunted around said device.

8. The. combination with an audion, of

a light sensitive device included in a circuit connecting the grid and filament electrodes of said audion, and a potentiometer included in said circuit and shunted around said device.

9. The combination with an audion, of a light sensitive device included in a circuit connecting the grid and filament electrodes of said audion, a source of current and a potentiometer included in said circuit and each shunted around said device.

In testimony whereof I have hereunto set my hand on this 12th day of September, A. 1)., 1919.

LEE DE FOREST. 

